As compared with a pure intensity modulated signal, a phase modulated optical signal has a higher spectral efficiency and a stronger anti-channel impairment capability. However, usually, an optical relay technology is applied for the intensity modulated signal, and if the existing optical relay technology is applied to the amplitude modulated signal, phase information of the signal will be lost, which limits the performance of the optical signal from being improved.
When the optical signal is transmitted, phase noises resulting from a transmission line may deteriorate the performance of the signal. In order to restrain the phase noise, an optical relay technology, that is, an optical regeneration method, is provided in the prior art. In the technology, the optical signal is converted to an electrical signal on a receiving end, and then the electrical signal is processed. The optical regeneration method is briefly described as follows.
Firstly, spectrum estimation is performed on the phase noise, that is, the phase information of the phase modulated signal is converted to intensity information through differential interference and balancing receiving. In other words, the optical-to-electrical conversion is performed on the information borne on the former signal, the phase information is recovered to the intensity information, and then a phase modulator re-loads the phase on the optical carrier phase by using the intensity information, so as to regenerate the phase.
During the implementation of the present invention, the inventors find that the optical regeneration method in the prior art at least has the following problems.
The method relates to a plurality of spectrum estimation methods, so that the implementation is complicated. In addition, an electrical processing speed is slow, which is not suitable for the processing of high-speed signals.